In general, a hydraulic excavator as a typical example of a construction machine comprises an automotive lower traveling structure, an upper revolving structure swingably mounted on the lower traveling structure, and a working mechanism mounted in a front side of the upper revolving structure in the front-rear direction to be capable of tilting up and down.
The upper revolving structure is configured by a revolving frame forming a support structure, a cab which is located in a front side of the revolving frame and onto which an operator gets, a counterweight located in a rear side of the revolving frame to act as a weight balance to the working mechanism, a prime mover such as an engine positioned in a front side of the counterweight and mounted on the revolving frame to drive a hydraulic pump, and a prime mover cover formed of a top surface part covering the prime mover from above, and a rear surface part hanging down from a rear end of the top surface part and making contact with a top surface of the counterweight.
The prime mover cover is configured such that a front portion of the top surface part is mounted to a structural body forming a part of the revolving frame by using a hinge member. Thereby the prime mover cover is provided to be rotatable (openable and closable) in the upper-lower direction with the front portion acting as the fulcrum. A striker is mounted on the top surface of the counterweight, and a latch is provided on the rear surface part of the prime mover cover to be engaged to the striker when the prime mover cover is closed, wherein the striker and the latch form part of a lock device (Patent Document 1).